• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.276-276
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• 2018

In this paper the potential of the Principle Component Analysis(PCA) technique that can be used to detect leaks in water pipe network blocks was evaluated. For this purpose the PCA was conducted to evaluate the relevance of the calculated outliers of a PCA model utilizing the recorded pipe flows and the recorded pipe leak incidents of a case study water distribution system. The PCA technique was enhanced by applying the computational algorithms developed in this study. The algorithms were designed to extract a partial set of flow data from the original 24 hour flow data so that the variability of the flows in the determined partial data set are minimal. The relevance of the calculated outliers of a PCA model and the recorded pipe leak incidents was analyzed. The results showed that the effectiveness of detecting leaks may improve by applying the developed algorithm. However, the analysis suggested that further development on the algorithm is needed to enhance the applicability of the PCA in detecting leaks in real-world water pipe networks.

• Structural Engineering and Mechanics
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• v.87 no.1
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• pp.69-84
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• 2023

The use of steel pipe dampers (SPD) as fuses or interchangeable elements in the steel moment-resisting frames (MRF) is one of the newest methods for improving seismic performance. In the present study, the performance of steel pipe dampers in MRF has been investigated. Evaluation of MRF with and without SPD models were performed using the finite element method by ABAQUS. For validation, an MRF and MRF with steel pipe dampers were modeled that had been experimentally tested and reported in previous experimental research and a good agreement was observed. The behavior of these dampers in frames of 3, 6, and 9 stories was studied by modeling the damper directly. Nonlinear time history dynamic analysis was used. It was observed that by increasing the number of stories in the buildings, steel pipe dampers should be used to perform properly against earthquakes. The installation of steel pipe dampers in steel moment-resisting frames shows that the drift ratio between the floors is reduced and the seismic performance of these frames is improved.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.61-66
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• 2008

As the water distribution system which is one of the critical lifeline system is deteriorated and pipe failures occur frequently, the more efficient pipe monitoring system becomes a critical issue in the water industry. One of the pipe monitoring systems is called "Smart-pipe System" which is permanent, comprehensive and an automated SIM (Structural Integrity Monitoring) system and has superiorities to existing monitoring system. To implement a smart-pipe system on a water distribution system, assessment of its indirect benefit obtaining from smartpipe such as the ratio of preventing water main failures must be preceded. However, only some researches on this field have been performed. In this paper, the concept of smart-pipe system is compared with the current monitoring systems for a water distribution system, and a method to quantify its benefit using the inconvenient time for customers is suggested. The suggested method was applied to a real water distribution system to estimate its applicability and benefit.

• Geotechnical Engineering
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• v.4 no.1
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• pp.49-58
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• 1988

The stresses on the buried steel pipe under embankment are analysed by the elasto-plastic theory using FEM to study the influences of the geometry of soil-conduit pipe system and the elastic modulus of the fill on the pipe responses . The geometry of the system considered in this study includes the height of embankment, the thickness of the pipe, and the width and the depth of the trench . By comparing the stresses computed by Marston-Spangler's pipe theory with those obtained from the elasto-plastic theory, Marston-Spangler's theory was discussed and analysed . It is found that the stress distribution around the pipe by elasto- plastic analysis is similar to that by Spangler's flexible pipe theory when the geometrical ratio (diameter/thickness) of the steel pipe is 400. And Spangler's flexible pipe theory does not seem to be suitable to analyse the buried steel pipe of which the geometrical ratio is lower than 200. The vertical loads by the rigid pipe theory are always larger than those by the flexible pipe theory regardness of the variations in the geometry of soil-conduit pipe system considered above and the elastic modulus of the fill.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.365-370
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• 2001

There are various wick types for heat pipe. In the present study, the manufacturing technology of a sintered wick among various wick types is discussed. The sintering technology using metal has been applied broadly in the field of electronic-telecommunication as well as heat pipes. A study of manufacturing procedure and characteristic of sintered wick for heat pipe have been performed. Copper powder was used as wick material and stainless steel as a mandrel. A manufacturing technology of the mandrel for arranging vapor core in heat pipe, a sintering technology by first or second times and operating temperature for sintering, the measurements of a porosity, pore size, and pore distribution of sintered wick were considered. In the meantime, a heat pipe with sintered wick has been manufactured and a performance test of the heat pipe has been performed in order to review cooling performance. The performance test results for the 4mm diameter heat pipe with the sintered wick shows the stability since the temperature difference between a evaporator and a condenser of the heat pipe is less than $4.4^{\circ}C$, and thermal resistance is less than $0.7^{\circ}C/W$.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.212-218
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• 1996

The concrete pipe used to distribute irrigation water to the right place now available is commonly made up of cement , sand, earth, pebble, etc. These materials with right ratio and right amount of water were mixed and squeezed through the pipe-making machine called vertical squeezed pipe-making machine, and then a cement prefabricated pipe is produced . This kinds of pipe has been expanding by leaps and bounds. Being little cement contents and low cost, the length of pipe is 1.0m or so with weight of 50kg, which is easy to be made and to be transported. The demolish pressure of it is 0.2 MPa or so, which meets the needs of agriculture irrigation . The buried pipe irrigation system, has been popularized in Jining Municipal , Shandong Province. By the year of 1995 , the irrigation area under pipe conveyancesystem usign this type of pipe has reached 74000 hectares. By calculation, about 27.7million ㎥ water, 2.88 million kWh power , 0.167 million man power and 1528 hectares cu tivated land will be saved one year, adding value of agriculture output increased by 10 million kg. The total economic benefits amount to 0.92 million US$ a year. The paper presents the pipe making course and its application on a large scale area.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.135-140
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• 2001

A simply supported pipe conveying fluid and a moving mass upon it constitute a vibrational system. The equation of motion is derived by using Lagrange's equation. The influence of the velocity and the inertia force of a moving mass and the velocities of fluid flow in the pipe have been studied on the dynamic behavior of a simply supported pipe by numerical method. The velocities of fluid low are considered within its critical values of the simply supported pipe without a moving mass upon it. Their coupling effects on the transverse vibration of a simply supported pipe are inspected too. as the velocity of a moving mass increases, the deflection of midspan of a simply supported pipe conveying fluid is increased and the frequency of transverse vibration of the pipe is not varied. Increasing of the velocity of fluid flow makes the frequency of transverse vibration of the simply supported pipe conveying fluid decrease and the deflection of midspan of the pipe increase. The deflection of the simply supported pipe conveying fluid is increased by a coupling of the moving mass and the velocities of a moving mass and fluid flow.

• Journal of KSNVE
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• v.9 no.4
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• pp.795-805
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• 1999

Rubber mounts so called grommets and pipes are two major paths of vibration transmission from a compressor, an important vibration source in an air conditioner, to the whole unit. A procedure of configuring the suction and discharge pipes of the compressor was developed in this paper so as to reduce the vibration transmission through the pipes as well as the grommets. Through investigating the effects of shapes and connecting disrections of pipe elements on vibration transmission, a guideline to configure the pipe layout, which enables to reduce vibration transmission, was proposed. The initial pipe layout by the guideline was optimized with the objective function, minimization of boty vibration transmission and the cost, and with the constraints to yield the final dimensions of the pipes. The procedure not only minimizes the transmitted force to the circumferential devices but enables to eliminate rubber blocks or dampers, which are generally used to avoid resonances of the pipe system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.403-408
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• 2007

The concrete pipe(Hume, PC) and polyethylene(PE) pipe are usually used for dram pipe in local market. Hume pipe, however, is heavy and needs the high cost of construction and PC pipe has a disadvantage to easily occur the deformation by the outside pressure even though it is light and constructible. The corrugated steel pipe coated with polyethylene is used increasedly because it is durable, constructible and economical. However, it is not used for sewage or waste water because it is hard to guarantee the watertight property on the coupling part. In this study, we studied on the flange coupling and the method of its construction to guarantee the watertight property and easy to use. If the developed flange coupling and method are used on a construction field, the economical property, constructible property and structural safety can be guaranteed.

• Land and Housing Review
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• v.7 no.4
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• pp.271-279
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• 2016

Recently developed trenchless construction methods ensure stability for the ground settlement by inserting steel pipes along the underpass section and integrating steel pipes before ground excavation to form pipe-roof. This study is to confirm the reinforcing effect of pipe-roof by measuring lateral earth pressure acting on the underpass constructed by the STS (Steel Tube Slab) construction method. For this purpose, lateral earth pressure was measured at the left and right side of the pipe-roof after installing earth pressure cells. As a result, lateral earth pressure was measured with considerable reduction because the integrated pipe-roof shared surcharge. Therefore, economic design for the underpass could be expected by sharing design load by pipe-roof. In addition, construction cost was analyzed according to the design-load sharing ratio by pipe-roof. As pipe-roof shares design load by 40%, the total construction cost can decrease by almost 10% in the case of four-lane underpass.